B-type insulation

ABSTRACT

A pair of electrical conductors are insulated by a common strip of B-shaped material having two lobes at opposite portions around respective conductors and a web connected between the lobes. The insulation is wrapped in opposite directions around the conductors from the longitudinal edges toward the center. The two lobes are brought close together and sealed to the web by adhesive. A portion of the web extends in a loop between the conductors and may be weakened along the length to facilitate severing the connection without damage to the insulation on either conductor. Undesired separation of pairs during jointing is eliminated.

United States Patent Ash [s4] B-TYPE INSULATION [72] Inventor:

[73] Assignee: International Standard Electric Corporation, New York, NY.

22 Filed: Feb. 8, 1972 21 Appl. No.: 224,472

[52] US. Cl ..174/117 R, 156/55, 174/27, 174/113 R, 174/124R [51] Intr Cl. ..l-I01b 7/02 58 Field ofSearch.... 174/124 R, 121 R, 121 B, 117 R,174/117 F, 119 R, 113 R, 27; 156/51, 52, 53,

Bernard Edwin Ash, Kent, England I 1451 Sept.26,1972

1,752,556 4/1930 Harrisonm... ..174/117 F X 1,714,716 5/1929 Hunter ..174/113 R 377,118 l/l888 Schefbauer ..174/124 R FOREIGN PATENTS OR APPLICATIONS 739,243 9/1943 Germany 174/1 17 R Primary Examiner-Lewis H. Myers Assistant Examiner-A. T. Grimley Att0mey-C. Cornell Remsen, Jr. et a1.

57 ABSTRACT A pair of electrical conductors are insulated by a common strip of B-shaped material having two lobes at opposite portions around respective conductors and a web connected between the lobes. The insulation is wrapped in opposite directions around the conductors from the longitudinal edges toward the center. The two lobes are brought close together and sealed to the web by adhesive. A portion of the web extends in a loop between the conductors and may be weakened along the length to facilitate severing the connection without damage to the insulation on either conductor.

,Undesired separation of pairs during jointing is eliminated.

6 Claims, 2 Drawing Figures B-TYPE INSULATION 1. Field of the Invention This invention relates to telephone cables and, in particular, to an arrangement enclosing a pair of insulated conductorswithin separate portions of a common strip of insulation material.

2. Description of the Prior Art A pair of insulated conductors for a telephone cable normally comprises two individually-insulated conductors which have been twisted together. The insulation may, for example, comprise longitudinally applied paper strip or an extruded plastics material.

When telephone cables consisting of pairs of conductors are jointed, it is not uncommon for the two insulated conductors which make up the pairs to become separated and. joined to insulated conductors in different; pairs offthe other cable. This results in a fault known as split pairs. One known arrangement for winding pairs of wires in acommon insulation strip is shown in US. Pat. No. 2,947,652, issued Aug. 2, 1960, wherein the insulation is formed in an S-shape. Another method and apparatus forms an insulation strip into a B-type configuration around a pair of separate conductors, as described in co-pending US. Patent application Ser. No. 187,044, filed Oct. 6, 1971 and assigned to the same assignee as the instant application.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a novel configuration which eliminates split pairs in joints between pair-type telephone cables wherein the conductors are insulated by a longitudinally applied strip of insulation'material.

According to one aspect of. thepresent invention there is provided an insulated pair of electrical conductors in which the insulating material therefor has a substantially B-shaped transverse section and an electrical conductor is positioned in each of the closed portions or lobes of the B, each lobe of the B forming a sealed tubearound its associated conductor, wherein the separate lobes are interconnected by a web of insulating material therebetween, and wherein the insulated conductors may be separated from one another, without damage to the insulation on either conductor by severing of the web.

According to another aspect of the present-invention there is provided an insulated pair of electrical conductors comprising two parallel electrical conductors wrapped in a single strip of insulating material, the strip being rolled up from both longitudinal edges to a substantially B-shaped transverse section having two closed portions or lobes which are interconnected by a web of insulating material therebetween, an electrical conductor being positioned in each of the lobes, wherein the lobes are sealed to the web by adhesive means to form a sealed tube around each conductor, and wherein the insulated conductors may be separated from one another, without damage to the insulation on either conductor, by severing of the web.

Embodiments of the invention will now be described with referenceto the accompanying'drawings.

2 BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows, in cross-section, a pair of insulated conductors, according to one embodiment of the invention, after a first manufacturing stage, and,

FIG. 2 shows, in cross-section, the pair of FIG. 1 after a second manufacturing stage.

DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIG. 1 two conductors l and 2 are shown wrapped in one piece of longitudinally-applied insulating strip material 3, each longitudinal edge of the strip material being wrapped toward the center in opposite directions on the same side of the strip around a separate one of the conductors to form a pair insulated by what is termed B-type insulation, the conductors being positioned respectively in the closed portions, or lobes, of the B. A method and apparatus for forming the strip 3 into such a B-type configuration around conductors l and 2 is described more fully in the above mentioned co-pending application. I

In order to maintain the insulation around each of the individual conductors, glue, or other adhesive means is providedbetween the portions of the strip wrapped around the conductors and the portions of the strip extending between the two conductors, that is,.in the gaps 4 and 5. The two conductors are brought together by a forming tool to the configuration shown in FIG. 2, with the interconnection portion of the strip forming a loop 6,. This bringing together of the conductors is such as to apply sufficient pressure to stick the opposing faces of the strip together with the glue or other means. The apex 7 of the loop 6 may be weakened, by for example, scoring, tosuch an extent that the strip may be readily split, without external tools, for separating the two insulated conductors for jointing, or other purposes, without fracturing the glued seams or otherwisedamaging the insulation on the two conductors. It is not absolutely necessary to weaken the interconnecting portion of the strip, since it may easily be cut with a knifeor. scissors when it is necessary to separate the conductors.

The conductors land 2 may, for example, be copper or aluminum, and the strip 3 may be of paper. Alternatively the strip 3 could be a plastics/paper laminate with the plastics side outermost, a suitable method being used to form a sealed tube of the laminate about each conductor. It is also possible to produce an insulated pair of conductors in the B-type configuration by extrusion of a plastics material, through a suitable die, over two parallel conductors.

The advantage of the present invention is that split pairs can thus be avoided, since the pairs of insulated conductors are maintained as pairs until the web of insulating material is severed, and since the pair to which any separate conductor belongs can easily be determined by tracing the insulation back to a point where the conductors are still joined.

What is claimed is:

1. An insulated pair of electrical conductors comprising a longitudinal strip of insulating material having two closed lobes wound toward the center from the longitudinal edges in opposite directions on the same side of the strip, and an electrical conductor positioned in each of the closed lobes, each lobe forming a sealed tube around its associated conductor, the separate lobes being interconnected by a web of insulating material therebetween.

2. An insulated pair of electrical conductors comprising two parallel electrical conductors separatelywrapped in a single strip of insulating material, the strip including two closed lobes rolled toward the center from both longitudinal edges in opposite directions on the same side of the strip to a substantially B-shaped transverse section, said lobes being interconnected by a 3. An insulated pair of electrical conductors as claimed in claim 2, wherein said separating means includes a partially weakened section along the length of the web to facilitate separation of the two insulated conductors.

4. An insulated pair of electrical conductors as claimed in claim 2 wherein said separating means includes a loop in the web extending outwardly between the sealed lobes.

5. An insulated pair of electrical conductors as claimed in claim 3, wherein the loop is partially weakened along its length to facilitate separation of the two insulated conductors.

6. An insulated pair of electrical conductors as claimed in claim 1 wherein the insulating material is paper. 

1. An insulated pair of electrical conductors comprising a longitudinal strip of insulating material having two closed lobes wound toward the center from the longitudinal edges in opposite directions on the same side of the strip, and an electrical conductor positioned in each of the closed lobes, each lobe forming a sealed tube around its associated conductor, the separate lobes being interconnected by a web of insulating material therebetween.
 2. An insulated pair of electrical conductors comprising two parallel electrical conDuctors separately wrapped in a single strip of insulating material, the strip including two closed lobes rolled toward the center from both longitudinal edges in opposite directions on the same side of the strip to a substantially B-shaped transverse section, said lobes being interconnected by a web of insulating material therebetween, an electrical conductor being positioned in each of the lobes, adhesive means sealing the lobes to the web to form a sealed tube around each conductor, and means for separating the insulated conductors from one another by severing of the web without damage to the insulation on either conductor.
 3. An insulated pair of electrical conductors as claimed in claim 2, wherein said separating means includes a partially weakened section along the length of the web to facilitate separation of the two insulated conductors.
 4. An insulated pair of electrical conductors as claimed in claim 2 wherein said separating means includes a loop in the web extending outwardly between the sealed lobes.
 5. An insulated pair of electrical conductors as claimed in claim 3, wherein the loop is partially weakened along its length to facilitate separation of the two insulated conductors.
 6. An insulated pair of electrical conductors as claimed in claim 1 wherein the insulating material is paper. 